In imaging devices which utilize light to form images, optical scanning systems are incorporated to scan laser beams from one or more light sources onto a photoconductive (PC) drum. A PC drum has a surface that is charged to a uniform potential by a charge roller, corona, etc. and selectively discharged to create a latent electrostatic image for development with toner for transfer to media.
When the coating thickness of the PC drum wears down as the PC drum is used over time, changes in the amount of charge that the PC drum can hold may occur. This affects the toner attracted to the PC drum, and consequently, to the toner that adheres to the media during imaging. The thinning of the PC drum coating therefore affects the darkness level produced by the PC drum which may gradually turn darker or lighter over the life of the PC drum. Some areas of the PC drum may also wear down faster than other areas which further causes inconsistency in the darkness produced by the PC drum. Depletion of toner from an attendant cartridge during use can also affect darkness, as smaller particles of toner first get imaged on the PC drum then larger particles of toner.
These and other factors may cause non-uniform darkness produced by the PC drum which, when left uncorrected, may become noticeable as a print quality defect to a user. As such, there is a need to maintain uniform darkness produced by the PC drum throughout the life of the PC drum.